In the prior art, a structure integrating a light-absorbing unit and a light emitting unit has been proposed for constructing OEIC (Optical Electrical Integrated Circuit) devices such as a light amplifier, a light switching element, a light transmitter, . . . etc. However, no one ever suggests a light converter based on this sort of structure. Moreover, most of the light-absorbing element and the light-emitting unit used in the structure are made of compound materials selected frown either common or different types of II-VI or III-V groups which are expensive due to their poor availability. Besides, the preparation of these materials requires a high-temperature process which results in the degradation of the light-emitting unit formed under the light-absorbing unit, and further degrades the performance of the entire OEIC device.